1. Field of the Invention
The present invention relates in general to valves and more particularly to ball valves for controlling fluid flow. The present invention is particularly adapted for valves used in the oil and gas industry.
2. Background
A ball valve of the type used in the oil and gas industry includes a ball valve element with an internal flow passage. The internal flow passage is aligned with inlet and outlet passages in the "open" position and placed out of alignment with the inlet and outlet passages in the "closed" position. Sealing members contact the ball valve element to provide a fluid tight seal between the inlet/outlet passages and the ball valve element. A seat assembly system is provided for maintaining the sealing members in an energized condition. Heretofore, various types of spring and seat assemblies have been utilized to urge the sealing members into sealing engagement with the associated ball valve member. As shown in U.S. Pat. No. 4,266,566 to Gary W. Kacal and Charles C. Partridge dated May 12, 1981, continuous wave springs are illustrated urging a valve seat assembly and resilient sealing ring into sealing engagement with an associated ball valve member.
In U.S. Pat. No. 4,477,055 to Charles C. Partridge dated Oct. 16, 1984, a ball valve structure is shown having a valve seat assembly positioned in annular seat pockets located in a flow passage on opposed sides of a ball valve member. Each valve seat assembly is mounted for limited longitudinal movement toward and away from the adjacent ball valve member and spring means are placed within the seat pockets behind the valve seat assemblies to urge the assemblies toward and into intimate contact with the ball valve member. The valve seat assembly includes inner and outer annular concentric seat rings with a resilient sealing ring secured therebetween. The inner annular seat ring has a flared end which fits inside the outer seat ring and energizes or deforms the sealing ring held therebetween, thereby, securely retaining the sealing ring between the seat rings and preventing the introduction of line pressure behind the sealing ring to possibly extrude the sealing ring from its position within the seat rings.
In U.S. Pat. No. 4,175,577 to Gary W. Kacal and Charles C. Partridge dated Nov. 27, 1979, a means and method for in-line removal of seat rings in ball valves is shown. A ball valve structure has a removable upper cover plate to permit the ball to be removed from the valve body. A separate cam tool (after removal of the cover plate) is positioned within the bore of the ball which has been partially rotated from the full open position, and upon a return rotation of the ball with the cam tool therein to a full open position an adjacent spring urged seat ring is cammed away from the ball to a retracted position. A seat ring retainer is then actuated to hold the seat ring in the retracted position. The cam tool is then utilized in a similar manner to cam the other opposite seat ring in the retracted position. The ball may then be removed with the seat rings for replacement or repair as desired. The seat rings and seals thereon may be removed and replaced in such manner without removal of the valve from the flowline in which the valve is positioned.